Spending more time sitting at your work desk or on the couch in front of the TV can increase your risk of dying from cancer, according to a new study, but getting up and moving can help mitigate the risk.
Lack of physical activity is a known risk factor for cardiovascular disease and other health problems. Although the link between sedentary behavior and cancer risk has been shown before, this was a large study and the association between inactivity and cancer mortality was strong.
“This is the first study that definitively shows a strong association between not moving and cancer death,” lead study author Susan Gilchrist, MD, of the University of Texas MD Anderson Cancer Center found in Houston, said in a press release. “Our findings show that the amount of time a person spends sitting prior to a cancer diagnosis is predictive of time to cancer death.”
As described in JAMA Oncology, Gilchrist and her team conducted a prospective cohort analysis that included 8,002 participants in the REGARDS (Reasons for Geographic and Racial Differences in Stroke) study who did not have a cancer diagnosis at the time of enrollment. Just over half were women, about 70% were white, about 30% were Black and the average age was about 69.
Unlike some past research that has relied on participant self-reports, the people in this study wore a hip-mounted accelerometer for seven consecutive days to objectively measure their sedentary time, light-intensity physical activity and moderate-to-vigorous physical activity.
According to the American Heart Association—which recommends that people get at least 150 minutes per week of moderate-intensity or 75 minutes of vigorous aerobic activity per week—moderate activity includes brisk walking, gardening or slow bicycling, while running, swimming laps or cycling faster than 10 miles per hour qualify as vigorous-intensity activity. For most people, walking at a normal pace would be light-intensity activity.
Over a mean follow-up period of about five years, a total of 268 study participants (3%) died of cancer.
After accounting for other factors, greater total sedentary time was associated with a higher risk of cancer mortality. In fact, the most sedentary participants had an 82% higher risk of cancer death than the most active people, the researchers reported. The amount of time spent sitting at a stretch was not significantly associated with greater cancer mortality as long as people got enough moderate-to-vigorous physical activity.
The study also showed that replacing 30 minutes of sedentary time with light-intensity physical activity was associated with an 8% decrease in cancer mortality, while substituting moderate-to vigorous activity was associated with a 31% risk reduction.
“Conversations with my patients always begin with why they don’t have time to exercise,” said Gilchrist, who leads MD Anderson’s Healthy Heart Program. “I tell them to consider standing up for five minutes every hour at work or taking the stairs instead of the elevator. It might not sound like a lot, but this study tells us even light activity has cancer survival benefits.”
Gilchrist said the researchers next step will be to investigate how objectively measured sedentary behavior impacts the incidence of specific types of cancer and whether sex and race play a role.
Click here to read the JAMA Oncology study.
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